On the right side of the location you will find a blue-red panel - use it with Spider-Man, to make a rope. Now choose Hulk and transform him into Bruce Banner (hold down change character button).
Climb on the rope and once more turn Bruce into a savage monster. Pull out green handles, destroying silo and scatter it into pieces. Build water cannon from debris and shoot at the enemy. Face him with Hulk and strike green wall with attack button.
Turn away and go to the central part of the arena. Find a pile of sand on the left and destroy it with Hulk's smash attack (simply press jump and attack buttons). Build concrete mixer from the debris and throw it at the enemy. When giant falls, hit him as before.
Approach blue-red panel on the left with Spider-Man and use spider's web to unlock a switch. Now pull it.
On the right side of the sand giant you will find silver obstacle, which only Iron Man can destroy. When it is done, use second switch to unlock the water tank.
When both switches are turned on, stand face-to-face with huge Sandman and use spider sense. When another blue-red panel appears, hit it with the web and pull out. In the end, knock down your enemy with Hulk.